Calculate how much each size per gram, and circle which gives the best value for money. 250g for $2.30, 400g for & 3.40, 1kg for $5.65

To do this, we must set up ratios:
Option One:

The first options costs only $0.0092/gram (a fraction of a penny)!
Option Two:

The second option costs only $0.0085/gram (cheaper than option one)!
Option Three: 
This requires a little more work. First, we have to convert the grams into kilograms. For every 1 kg, there is 1,000 g. Therefore, 1,000g costs $5.65. Next, we set up the ratio as usual:

The third option costs $0.00565/gram.

Therefore, option three is the cheapest! 

Hope this helps!